Sure, here is an optimal plan to solve the problem:

1. "open" action: Open the boot.
2. "fetch" action: Fetch the jack from the boot.
3. "fetch" action: Fetch the wrench from the boot.
4. "fetch" action: Fetch the pump from the boot.
5. "fetch" action: Fetch an intact tyre from the boot.
6. "inflate" action: Inflate the intact tyre with the pump.
7. "put-away" action: Put the pump back in the boot.
8. "jack-up" action: Jack up the first hub.
9. "loosen" action: Loosen the nut on the first hub with the wrench.
10. "undo" action: Undo the fastening of the nut on the first hub.
11. "remove-wheel" action: Remove the flat tyre from the first hub.
12. "put-away" action: Put the flat tyre in the boot.
13. "put-on-wheel" action: Put the inflated intact tyre on the first hub.
14. "do-up" action: Fasten the nut on the first hub.
15. "tighten" action: Tighten the nut on the first hub with the wrench.
16. "jack-down" action: Lower the first hub back to the ground.
17. Repeat steps 5-16 for the remaining 7 hubs.
18. "put-away" action: Put the wrench back in the boot.
19. "put-away" action: Put the jack back in the boot.
20. "close" action: Close the boot.

This plan ensures that all flat tyres are replaced with inflated intact tyres, all tools and replaced tyres are put back in the boot, and the boot is closed at the end.